The subject matter herein relates generally to light pipes and, more particularly, to an assembly for the distribution of light from one or more light sources to one or more light pipes.
Current lighting systems comprise a light source, such as Light Emitting Diodes (LEDs), and a light pipe to distribute the light in the desired configuration. In some applications, more than one light source and/or more than one light pipe may be provided. For example, two LEDs may be used with two or more light pipes. In some applications, it is desirable to have equal average optical pathways from any of the two LEDs to any light pipe to provide equal light inputs for both light pipes. However, conventional lighting systems using light pipe assemblies have problems collecting light from either one of multiple possible light sources and then distributing the light to two or more separate light pipes along equal average optical pathways. In current assemblies, due to the geometry of the assemblies and/or the wavelength selective absorption of transparent plastic materials, light arrives on target in interlaced chromatic spots.
White light emitting LEDs can be produced either by superposing red, green, and blue light emitted by three semiconductor dies embedded into the RGB LED, or in the case of the standard white LED, color subtraction produced by a phosphorus layer within the semiconductor of a blue LED. However, both the RGB and the standard white LED might present noticeable spatial color variation due to selective wavelength absorption that characterizes all optical media, especially transparent plastic materials. Moreover, the refractive index of a material is dependant of the light wavelength. This applies also to the standard white LED as it is defined by a wave spectrum.
As the LED emission is Lambertian, it will lead to uneven spatial flux distribution and color participation into any cross section of the coupling secondary optics. In order to maintain a relative even spatial distribution both in respect to luminous flux and chromaticity, random light shuffling may be used. The existing methods adopted for color mixing include transmissive optics, reflective optics, or diffusing optics. Diffusing optics are characterized by high degree of light absorption that makes them not suitable for light pipe applications. Using transmissive and reflective optics requires long pathways to achieve a high number of reflections.
A need remains for a cost effective light distribution assembly for distributing light from either one or more light sources (e.g. LEDs) to two or more light pipes while preserving the desired color intensity from the different LED combinations.